1. Field of the Invention
The present invention relates to an electronic music tone generator applied to apparatuses such as electronic musical instruments, Karaoke apparatuses, DTM (Desk Top Music) apparatuses, and the like for electronically generating music tones using sound source LSIs (Large Scale Integrated Circuits) made up of CMOSs (Complementary Metal Oxide Semiconductors).
2. Description of the Related Art
Conventionally, an electronic musical instrument that can time-divisionally produce a plurality of tones to sound at the same time is known. Such electronic musical instrument time-divisionally reads out waveform data of music tones corresponding to keyboard operations from a waveform ROM (Read Only Memory), and assigns them to tone generation channels (music tone generation channels) to produce tones, so that the number of tones that can be simultaneously produced in accordance with the number of channels prepared for generating music tones.
In the above-mentioned conventional electronic musical instrument, a speaker drive circuit consumes the largest electric power, and requires electric power about an order of magnitude larger than that of a tone generator even at normal tone volume.
In view of this problem, a digital electronic musical instrument which attains power savings using a 3 V power supply in place of a popular 5 V power supply by omitting a speaker is known.
However, such electronic musical instrument cannot attain power savings more than electric power required for the speaker.
More specifically, since the conventional electronic musical instrument can attain power savings by omitting the speaker but does not aim at attaining power savings by the tone generator itself, total power savings cannot be done.
Especially, since the tone generator of the conventional electronic musical instrument time-divisionally makes arithmetic operations for all the prepared channels regardless of used or unused channels, electric power required for the arithmetic operations for unused channels is wasted.
For this reason, a battery-driven electronic musical instrument or the like can only be used several days due to the service life of batteries.